I figured it would be good to have a quick tutorial on using Print Screen (strangely enough using Print Screen! )
(Unfortunately I don't know the process for Macs, so this will just be for PCs.)
Step 1:
Hit "Prnt Scrn" button on top-right of keyboard, usually near Num Lk and above the high F keys (F10, F11, etc.)
Step 2:
Open up Microsoft Paint (or other picture editing program that you are comfortable with).
Step 3:
With Paint open, hit Crtl+V, should look like this:
Step 4:
a ) Select the crop tool
b ) Select area to crop
Step 5:
Hit Crtl+X, and open new file.
Step 6:
Hit Ctrl+V, and click "save as", saving the file as whatever you'd like.
Once you've saved it, you can upload it to the site using the method of your choice.